Mini Big Bertha PDF Available!

[hcmbanjo]

I just finished up a new carded downscale of the Estes classic
BIG BERTHA
This scheme is based on the color picture from the 1969 Estes catalog.

The FREE PDF includes a BT-5 body skin wrap and cardstock fins.
It stands 7 3/4" tall and flys with 1/2A3-2t and A3-4t engines.

Bob Harrington had already produced a great carded MiniBrute version of the Bertha.
Mine is a little different in that you use a BT-5 and apply a printed skin over the tube. There is no painting except for the nose cone.
The fin overlays are made with a rounded leading edge.

You can get the whole story on my Model Rocket Building Blog at:
https://modelrocketbuilding.blogspot.com/2011/03/mini-big-bertha-pdf-now-available_25.html

Download your free PDF at Wayne Hill's Rocketry Blog at:
https://rocketry.wordpress.com/ultimate-paper-rocket-guide/paper-rocket-partial-builds/
Scroll all the way down to the bottom for the Mini Bertha.

 

[cwbullet]

Great card build.

 

[JPVegh]

Dig it!

Thanks for posting this.

 

[Socknic]

Thank you for posting this! I had never built a paper rocket, and this was great. I was actually at a loss of parts when I built this rocket. I used balsa fins, created a entirely card stock body tube, and carved a nose cone from foam stuff. I took this to the field when it was windy, and expected to lose it. When I launched it, it soared upward, reached apogee, and the streamer deployed. I actually got the rocket back. Anyway, it was a great rocket.

 

[hcmbanjo]

Thank you for posting this! I had never built a paper rocket, and this was great. I was actually at a loss of parts when I built this rocket. I used balsa fins, created a entirely card stock body tube, and carved a nose cone from foam stuff. I took this to the field when it was windy, and expected to lose it. When I launched it, it soared upward, reached apogee, and the streamer deployed. I actually got the rocket back. Anyway, it was a great rocket.

I'm glad to hear it flew well!
Good work making up your own parts.
Try the three ply card fins sometime. They are much stronger than you'd think.
My Mini Bertha needed a little nose weight.

There are plenty of other free carded models available on Wayne Hill's website.
https://rocketry.wordpress.com/ultimate-paper-rocket-guide/paper-rocket-partial-builds/
Scroll down all the way to the bottom for my PDF plans.

I just added another today, the Centuri Astro 1.
https://modelrocketbuilding.blogspot.com/2011/08/astro-1-downscale-free-pdf.html

 

[BobH48]

Chris,

Nice Bertha downscale. I am interested to see how the body wrap holds up using a glue stick. I've tried glue sticks before with varying success.

When rolling double thickness tubes, they don't seem to give it the same solid feeling that you get with Elmer's white glue but since the BT-5 is there for the strength, then the glue stick only needs to hold on the wrap.

 

[hcmbanjo]

Hi Bob,
I'm expirimenting with the gluestick, always looking for the next "better" thing.
I like it (so far) because I can reposition the wrap before it sets up. White glue can get the wrap too wet and there isn't much time to set it down.

The glue stick works over most of the body tube wrap. The butted seam might start to lift, that's when I go back and sneak a little white glue under the seam. I usually apply a small line of glue on one side of a single edge razor blade to get it under the raised edge.

I haven't really found a good spray adhesive. The seams still want to lift and even with adhesive sprays I still have to use a little white glue afterwards.

 

[gpoehlein]

Something I've been meaning to try but haven't had the chance yet is to coat the body tube with a thin layer of white glue, let that dry, then apply the wrap with a monocote iron. I don't know if I need a coat of dry glue on the wrap as well or not. When I get the chance...

 

[plastic_gorilla]

Great little kit. Built it the other night, my printer does aweful with color recently, so break out the sharpies. I went ahead and rolled the bt out of cardstock by leaving an extra 1/4" flap on the bt wrap, and i built the nosecone by rolling a tube and cutting some triangles out of the top, created a small plug to go inside and glued the top down to create a rough nosecone. Then I built it up with wood putty, figured the weight could only help, sand prime paint.

will be ready to fly this weekend!

 

[MarkII]

Nice downscale!

Now we just need a Maxi Mini Bertha and a Giant Baby Bertha!

 

[MarkII]

Wait, I just remembered - Estes already makes an upscale of the Mini Bertha!